Opacifier for enamels



- y; NoDraw ingHh-V 7 Patented Dec'. 2, 1930 THOMAS H. ucxnowlv; oF-METcHEN; NEW JERSEY, AssIeNonrY MEsnEiAssisiv :MENTS, To THE ROESSLER.annssreonma .cH IoAL'oo PAnY, A-OLORPQRATIQN OF DELAWARE inventionrelates toi thie manufacture t je tflp videsuchfan enamel particularlysuited for useon sheet metal I n such as sheet iron and sheet steel.

tin oxide asopacifier. have triedvarious mixtures of-sodium antimonateand tin oxide in a number of varied formulae, but l have is an that thebest'results aregsecuredif the two constituents are'present'lnamoreorless Y isaltered in eitherdirection the enamel in .whi'chitaisused does not have-the desired opacityand physicalpropertiee. have foundthat in the enamels of my; invention this-"3 i lmixture, can beutilizedin amounts Li 25 su flicientp to give desired opacity and]bolor,

and s'till not render the enamel brittleor in 'crea'seit's tendency tochi-pofi i. eltheproper cubical expansionloit the enamel ne'eessarytosecure the proper adherence-to the; sheet iron opacifier. V p a '1. Ihave further discovered that to secure the proper adherence and otherdesirablequalities Iin such enamels several components iiiust beu'sed'in more or'less"defini te1pro- ;portions. The following '1 "examle gives these components in the preferred pp'ropon W49 tions andthe'variable allowances: which may be made the components to securesmall variations in the expansion-.coefficient 110-0011 form to thesheet steel. The individual coefiicients of expansion of the componentsare givenlin the literature so that having the basic formula given herebelow thedesired composition can be made upntofit anyparticular sheetsteel.

v a In this example and in the appended claims my =opacifier-isreferredto as antimony-tin 7 My invention consists in providing enamelmixtures containlng sodiumjantlmonate and 7 orAcrrrnnv-roa nner/[Eris JShet steel enamel formula W The powdered materials of .the frit formulaare mixed by han'd'or mechanically, and then .fused the melt isdrQppedinto Water to cool and shatter after which it is placed in the ball milltogetherwith the remaining constituents of themillibatch;*Thesematerials arethen ground together'in the mill to afineness best suited for the particular method ofapplication to beused;this finenes'sxwill be generallybetween about 30 7O'mesh. r

using this enamel on sheet steel an under coating or abinding coatisfirst applied to the article; This undercoat may be,

any ofthe wellknown coat compositions suited for the-articles which arecommonly used. These undercoats are essentially an enamelglasscomposition containingno opacifier, and preferably containing cobaltoxide and manganes'e oxide. The undercoatingi 'is first applied'to thesteel and burned on,or fired, at a temperature somewhat higher than thatrequired to mature the enamel given above. T -This temperature will? be;above I he 1 ferred Variable-nit frit allowances fm-mnla fFeldspaflpatts byvwt 25. 2 24 to '27 Flmt (parts by wt 16.9 15 to 18Borax (partsby wt 25.0 23,130 27 Soda n tre (parts by wt a 3. 0 1 to 4Soda'ash' (parts by Wt. 4. 1 3 to '5 Cryolxtelparts by wt 13. 9 11 to 14Fluorspar (parts by wt.) 2. 9 2 to 5 Wlntlng (parts by wt.) 3. 0 71 to 4Antimony tm opaclfier (parts by ,wt.) 6. 0 l'to 12 Mill batch 1 rp V.ferred Variable a1- batch 'lowances formula H j Enamel frit (parts bywt) 100. 0 100 Clay (parts by wt.); 6 4 'to '6 Antimony tinopacifierqiarts by w 2 1 to, 8 MgSO4 plus 7HaO (parts by Wt.)' .'5 r l.4 to 8 Water (parts by wt.). 35 25 to 40 v- 7 Mols. Na|20 K 0 0.062 CaO0.208 A1 0 0.279 B 0 0.38 1 Sb O 0.038 Si0 1.770 SnO 0.03s F O/lOeL Thecoefiicient of expansion obtained with the preferred formula is 329.2 X10.

The variable compositions allowable in this flux will result in fluxeshaving a variable composition by weight approximately as follows:

Na O 12 to 18 K 0 2 to 2.2 CaO 2.5; to 6.0 A1 0 V 8.6 to 11.0 B 0 8.4;to 10.0 Sb O 0.6 to 8 SiO 33 to 40 SnO 1 to 8 F l 1 to 6 In the aboveformulae it will be noted that the opacifier allowances cover a widerange; the actual amount to be used depends on the opacity desired. Inthe above example part of the opacifier has been added in the enamelformula and part in the mill batch. This, however, is an optionalprocedure and depends upon the color desired in the enamel. Theopacifier can all be added to the raw frit formula before smelting, orit can all be added to the mill batch, or it can be distributed betweenthe twobatches in the amounts indicated above or in any other desireddistribution. If all of the opacifier is added to the mill batch theresulting enamel will have a slight creamy tint, whereas if all of theopacifi-er is added to the raw frit batch before smelting a bluish whiteenamel results; if the opacifier is distributed between the two batchesthe tint will vary between the two extremes in about the ratio of theadditions.

lVhile I have explained the opacifier as being a definite mixture of thetwo materials, I have found that it is not necessary to actually mix orgrind the antimonate and tin oxide together before adding them to theenamel. I have found that the opacifying results are equally wellsecured if, for example, the two were mixed prior to the addition of theenamel, or whether they were added separately, the only requirementbeing that the ratio approximately be maintained. Furthermore, I havefound that all of the antimonate can be added to the raw frit formulaand the tin oxide added. to. the mill batch. .Regardless of how the twomaterials are added any deviation from the ratio 3: 1 is immediatelyapparent by a change in the appearance and properties of the enamel. Itcan be seen from theabove I do not wish to be limited tothe manner ofadding my opacifying mixtures to the enamel. The sodium antimonate of myantimonytin opacifier may be supplied by pure sodium antimonate as such,or I may use the material commonly known in the art as leukonin whichconsists chiefly of sodium antimonate, and therefore in the appendedclaims, I wish it understood that sodium antimonate is intended to.cover such mixtures, and the term antimony tin opacifier is intended tocover such materials as leukonin in combination with tin oxideas well asthe pure material. It is to be noted that in the fired enamelcomposition as given above that the antimony oxide and tin oxide arepresent in a ratio of approximately 1 :1.

Formulae suited for wet and dry process cast iron enameling embodying myinvention are given in my copending applications SerialNo. 246,399 andSerial No. 246,398 respectiyely filed of even date herewith.

Claims: A

1. Method of producing a clouding or opacifying' effect in white enamelswhich comprises incorporating with the enamel sodium antimonate-and tinoxide in approximately the ratio of three parts by weight of sodiumantimonate to one partof tin oxide.

2. An enamel composition comprising:

Frz't formula Parts by v weight Feldspar 24 to 27 Flint 15 to 18 Borax l23 to 27 Soda nitre 1 to 4. Soda ash 3to 5 Cryoliteh 11 to 14 Fluorspar2 to 5 Whiting 1 to 4; Antimony-tin opacifier (3 1) 1 to 12 M ill batchParts by weight Enamel frit 100 Clay 4 to 6 Antimony-tin opacifier (3 1)1 to 8 MgSO plus 7 H O .4 to .8 Water Y 25 to 40 I weight I Feldsparnn;-i 25.2 Flint 16.9 Borax i 1 25.0 Soda nitre; 1 3.0

' Soda ash 4.1 Cryolite; 13.9 Fluorspar 2.9 Whiting 3.0 Antimony-tinopacifier 6.0

. V 100.0 1 Mill batch. 3

' .Partsby r weight Enamel frit Clay I I Antimony-tin opacifier (3: 1) 2MgSO plus 7H O .5 Water .1 35' Weight. approximately as follows:

- t Partsby I weight Na O 12 to 18 K 0 2 to 2.2 020; 2.5to 6.0 A1 0 8.613011.0 B 0 8.4:t'o 10.0 Sb203 t0 8 I S510 33- -to40 sn0 1-to8 F 4 to 6'wherein sodium antimoniate and tin oxide are utilized in the requisiteamount in-the preparation of the composition for firing and in the ratioto each other of3to 1. V

5. A fired enamel having the following empirical vformula: I Mols Na O0.730 K 0 0.062 OaO 0.208 A1203 I 'V.. V .-I- B203 .V ..I 819 0 0.038SiO 1.770 SnO 0.033 F 0.404 I 6. An enamel composition forthe'production of White enamel containing sodium anti- I monate and tin oxide inratios of three to one.

' 7. A fired white enamel'containing anti mony oxide and tin oxide inratios of approximately one to one. I Signed at Perth Amboy, in thecounty of 3. An enamel composition comprising Fm't fomula.

4. A fired enamel having a composition by A Middlesex and State 10ftenth day of January, A. D. 1928.

THOMAS H. MOKEOWN. I

Parts by I New Jersey. this

